The management of cervical disease is changing worldwide as a result of HPV vaccination and the increasing use of HPV testing for cervical screening. However, the impact of vaccination on the performance of HPV based screening strategies is largely unknown. Projects such as the SHEVa (Scottish HPV Prevalence in Vaccinated women) studies are designed to gain insight into the impact of vaccination on the performance of clinically validated HPV assays.
Samples collated from women attending for first cervical smear who had been vaccinated as part of a national “catch up” programme were tested with three clinically validated HPV assays (2 DNA and 1 RNA) and one highly sensitive, epidemiologically orientated assay. Overall HR-HPV and type specific positivity was assessed in the total population and according to underlying cytology and compared to a demographically equivalent group of unvaccinated women. A separate analysis of test performance in samples obtained from immunised women and enriched for cytological abnormalities was also performed
HPV prevalence was significantly lower in vaccinated women and was influenced by assay-type, reducing by 23-25% for the DNA based assays and 32% for the RNA assay (p=0.0008). All assays showed over 75% reduction of HPV16 and/or 18 (p<0.0001) whereas the prevalence of non 16/18 HR-HPV was not significantly different in vaccinated vs unvaccinated women. In women with low grade abnormalities, the proportion associated with non 16/18 HR-HPV was significantly higher in vaccinated women (p<0.0001). Data on clinical performance of the assays using the disease-enriched samples will be presented
Clinically validated HPV assays are affected differentially when applied to vaccinated women, dependent on assay chemistry. The increased proportion of non HPV16/18 infections may have implications for clinical performance, consequently, longitudinal studies linking HPV status to disease outcomes in vaccinated women will provide welcome insight.